The default SGA attach address for shared memory segments in Oracle 9i on Red Hat Enterprise Linux 2.1 is 0x50000000 (1.25 GB). To lower the SGA attach address for shared memory, the Oracle utility genksms must be used before the relinking:

# Create a new ksms object file
make -f ins_rdbms.mk ksms.o
# Create a new "oracle" executable ($ORACLE_HOME/bin/oracle):
make -f ins_rdbms.mk ioracle
# The last step creates a new Oracle binary in $ORACLE_HOME/bin
# that loads the SGA at the address specified by sgabeg in ksms.s:
# .set sgabeg,0X15000000